A remote parking assist (RePA) system is designed to autonomously park a vehicle. The RePA system may be used when an operator of the vehicle is sitting in the driver's seat and not grasping the steering wheel. Often, the RePA system is used when the operator is outside the vehicle. The operator triggers the RePA system to park or un-park a vehicle into or out of a parking space using a mobile device wirelessly communicating with the vehicle. Governments are developing regulations to require that control of RePA with the mobile device shall only be allowed when the remote device is within a certain distance of the vehicle. For example, the proposed European regulation requires the mobile device to be within 6 meters of the nearest point of the motor vehicle (see Economic Commission for Europe, Regulation No. 79) in order for the vehicle to autonomously park. However, it is difficult to accurately measure a distance of 6 m from the nearest point of the vehicle with the wireless technologies commonly available on commercial mobile devices. For example, civilian frequencies for global positioning system (GPS) receivers have a 4 meter root mean squared (RMS) horizontal accuracy. As a consequence, comparing the GPS coordinates of the mobile device and the GPS coordinates of the vehicle is not accurate enough to meet the governmental requirements.